This invention is a process for manufacturing lithium niobate polarization splitters using nickel (or zinc) diffusion. Y-branch polarization splitters, which are the product of this invention, have high extinction ratio and can meet the requirements of practical applications.
According to U.S. Pat. No. 5,436,992, the manufacturing process for the polarization splitter using a single-polarization waveguide on lithium niobate (shown in FIG. 1) includes 3 manufacturing techniques: titanium diffusion (for producing a common (ordinary) and uncommon (extraordinary) polarized light waveguide), nickel diffusion (for producing an ordinary polarized light waveguide) and magnesium oxide diffusion or proton exchange method (for producing an extraordinary polarized light waveguide). By using the characteristics of single polarization waveguide elements, the device can have high extinction ratios. Since it takes three manufacturing techniques to produce these elements, the manufacturing process is not simple enough for practical applications.